Self locking and unlocking elevator assembly

Abstract

A self locking and unlocking elevator for use with drill pipe is disclosed which, in a specific embodiment, includes a cam body which defines two symmetrically positioned cam surfaces. Each of these cam surfaces serves to support the upper end of a respective jaw, the lower end of which is shaped to clamp and hold the box end of a length of drill pipe. A collar is disposed around the jaws and is mechanically interlocked with the jaws such that both the collar and the jaws are suspended from the cam body. A plate is positioned below the collar above the box end of a clamped length of drill pipe and is secured to the cam body so as to move between a lower position in which the collar and jaws hang from the cam body, and an upper position in which the jaws are supported via the collar and the plate by the box end of the clamped drill pipe. The jaws are shaped such that they move by force of gravity to a closed clamping position when suspended from the cam body, and they open to release the drill pipe when supported by the movable plate.

I claim: 
     
       1. An elevator for drill pipe, comprising: at least two jaws, each jaw having a clamping surface shaped to support a length of pipe;   pivot means for urging the clamping surfaces of the jaws into contact with a length of pipe to be elevated, when the ends of the jaws distant from the clamping surfaces are urged away from the pipe;   elevator suspension and jaw activating means for suspending the elevator, for urging the ends of the jaws distant from the clamping surfaces away from the pipe, and in conjunction with the pivot means, for urging the clamping surfaces into contact with the pipe, when the elevator suspension and jaw activating means and the pipe are urged away from each other; and   release means for urging the clamping surfaces away from the pipe when the elevator suspension and jaw activating means and the pipe are urged toward each other.   
     
     
       2. The invention of claim 1 wherein the elevator is so configured that upon lowering the elevator upon a vertical length of drill pipe held within the jaws of the elevator, the release means automatically urges the clamping surfaces away from the pipe, whereby to release the pipe. 
     
     
       3. The invention of claim 1 or 2 wherein the elevator is so configured that upon raising the elevator with a vertical length of drill pipe held within the jaws of the elevator, the elevator suspension and jaw activating means automatically urges the clamping surfaces toward the pipe, whereby to clamp firmly onto the length of pipe. 
     
     
       4. The invention of claim 1 or 2 wherein the elevator is so configured that upon raising the release means when no drill pipe is held within the jaws, the jaws open to receive a length of pipe. 
     
     
       5. An elevator for drill pipe, said elevator comprising: a cam body having an attachment member and at least two spaced cam surfaces;   at least two jaws, each having an upper support surface in contact with a respective one of the at least two cam surfaces and a clamping surface shaped to support a length of pipe;   a collar;   means for engaging the collar on the jaws such that the weight of the collar is supportable on the jaws at a point below the cam surfaces and the jaws are pivotable with respect to the collar, the weight of said collar tending to cause the clamping surfaces of the jaws to approach one another to grip a length of pipe positioned therebetween; and   means for raising the collar with respect to the cam body to cause the clamping surfaces to separate from one another to release a length of pipe positioned therebetween.   
     
     
       6. The invention of claim 5 wherein the attachment member defines a support axis and the at least two cam surfaces are symmetrically positioned with respect to the support axis. 
     
     
       7. The invention of claim 5 wherein each of the at least two cam surfaces forms the inner surface of a respective recess formed in the cam body. 
     
     
       8. The invention of claim 5 further comprising at least two pins, each positioned in a respective one of the jaws above the collar to prevent the respective jaw from falling through the collar. 
     
     
       9. The invention of claim 5 wherein the engaging means comprises: a shoulder formed on each of the jaws adjacent the collar; and   interlocking recesses formed in the collar to receive the shoulders in order mechanically to engage the jaws with the collar.   
     
     
       10. The invention of claim 5 wherein the raising means comprises: a plate; and   means for movably connecting the plate to the cam body such that the plate is movable between a lower position, in which the plate is situated beneath the collar, and an upper position, in which the plate supports the collar;   said plate positioned to contact a length of pipe centered in the jaws.   
     
     
       11. A self locking and unlocking elevator for drill pipe, said elevator comprising: a cam body having an upper attachment member adapted to support the cam body, a lower recess aligned with the upper attachment member, and at least two cam surface defining grooves symmetrically disposed around the periphery of the cam body;   at least two jaws, each having an upper support surface disposed in a respective one of the cam surface defining grooves and a clamping surface shaped to hold a length of pipe on a clamping axis;   a collar disposed around the jaws;   means for mechanically interlocking the jaws with the collar such that the jaws are pivotable with respect to the cam body and the collar, the mechanical interlock means configured such that the jaws tend to close into a clamping position when the jaws and collar are suspended from the cam body, and the jaws tend to open into a release position when the jaws are supported by the collar;   a retaining shaft disposed to move longitudinally in the lower recess of the cam body; and   a plate mounted to the retaining shaft below the collar and movable between an upper and a lower position, said plate passing across the collar between the jaws such that upward forces on the plate act on the collar to lift the collar;   the jaws, collar and cam body configured automatically to clamp a length of drill pipe positioned between the lower surfaces of the jaws when the plate is positioned in the lower position and the jaws and collar are suspended from the cam body, and automatically to release a clamped length of drill pipe when the plate is raised to the upper position.   
     
     
       12. The invention of claim 11 further comprising means for defining at least two lugs, each positioned on a respective one of the jaws above the collar, each shaped and dimensioned to prevent the respective jaw from passing through the collar in the event of a failure of the mechanical interlock means. 
     
     
       13. The invention of claim 11 wherein the attachment member is centered on the clamping axis and the at least two cam surface defining grooves are symmetrically disposed with respect to the clamping axis. 
     
     
       14. The invention of claim 11 wherein the mechanical interlock means comprises: at least two recesses formed in inner surfaces of the collar in alignment with respective ones of the at least two jaws; and   at least two protrusions, each positioned on a respective one of the jaws to fit within the respective recess and to create a mechanical interlock between the respective jaw and the collar.   
     
     
       15. An automatically locking and unlocking elevator for drill pipe, said elevator comprising: a cam body having an attachment member and at least two spaced cam surfaces;   at least two jaws, each having an upper support surface in contact with a respective one of the two cam surfaces and a clamping surface shaped to support a length of pipe;   a collar;   means for engaging the collar on the jaws such that the weight of the collar is supportable on the jaws at a point below the cam surfaces and the jaws are pivotable with respect to the collar, the weight of said collar tending to cause the clamping surfaces of the jaws to approach one another to grip a length of pipe positioned therebetween;   means for automatically opening the jaws to receive a length of drill pipe when the elevator is lowered over the length of drill pipe to clamp the length of drill pipe; and   means for automatically raising the collar and thereby opening the jaws to release the clamped length of drill pipe when the elevator is lowered with respect to the clamped length of drill pipe.   
     
     
       16. The invention of claim 15 wherein the raising means operates to move the jaws upwardly along the cam surfaces. 
     
     
       17. The invention of claim 15 wherein the raising means comprises: a plate positioned between the jaws under the collar;   means for securing the plate to the cam body such that the plate is movable between a lower position, in which the plate is spaced from the collar, and an upper position, in which the plate supports the collar and the jaws.   
     
     
       18. The invention of claim 15 or 17 wherein the opening means comprises beveled inner surfaces, each defined by a respective one of the jaws below the respective clamping surface. 
     
     
       19. The invention of claim 15 or 17 wherein the engaging means comprises: a shoulder formed on each of the jaws adjacent the collar; and   interlocking recesses formed in the collar to receive the shoulders in order mechanically to engage the jaws with the collar.   
     
     
       20. The invention of claim 15 wherein the attachment member defines a support axis, and the at least two cam surfaces are symmetrically positioned with respect to the support axis. 
     
     
       21. The invention of claim 15 wherein each of the at least two cam surfaces forms the inner surface of a respective recess formed in the cam body. 
     
     
       22. The invention of claim 15 further comprising at least two pins, each positioned in a respective one of the jaws above the collar to prevent the respective jaw from falling through the collar. 
     
     
       23. The invention of claim 5 wherein the jaws are free of load bearing contact against one another in the region between the jaws and aligned with the collar. 
     
     
       24. The invention of claim 5 wherein the static weight of the collar and the jaws operates automatically to close the jaws when the jaws and collar are supported on the cam body.